One or more embodiments of the present invention relate to a camera module and a position detector and a position detection method used in the camera module, and more particularly, to a camera module capable of accurately detecting a position of a lens barrel that is driven along at least two axes and a position detector and a position detection method used in the camera module.
A digital camera is a device capable of storing an image of a subject as a digital file such as a picture or a video image; examples of the digital camera include a digital still camera (DSC), a digital video camera (DVC), and a digital camera module mounted in a mobile phone.
As digital photographing apparatuses such as DSCs and/or DVCs are frequently supplied, consumer demand for high-quality still images and/or video is increasing. In particular, the demand for a camera module having an optical image stabilization (OIS) function for preventing a decrease in image sharpness due to handshaking of a user is increasing.
In order to perform optical image stabilization, a camera module may move a lens barrel two-dimensionally, in a direction that is perpendicular to an optical axis. To control two-dimensional movement of the lens barrel, a two-dimensional position of the lens barrel has to be detected accurately.
One of methods of detecting a two-dimensional position of the lens barrel may be a method of detecting a position by using a magnetic flux density of a magnet. For example, a magnetic sensor may be disposed spaced apart from a magnet that is used in moving a lens barrel a predetermined distance, and the position of the lens barrel may be detected by a detection signal detected by the magnetic sensor. At least two magnetic sensors may be disposed to detect a two-dimensional position of the lens barrel.
The above-described magnetic sensor may determine a position of the magnet that slidably moves with respect to the magnetic sensor. For example, while being spaced apart from the magnet by a predetermined distance in a first direction, the magnetic sensor determines a position of the magnet that moves in a second direction perpendicular to the first direction. The principle of determining a position of the magnet by using the magnetic sensor assumes a predetermined distance between the magnetic sensor and the magnet in the first direction, and accordingly, this method may not be used in determining a position of the magnet in the second direction under a condition where the distance between the magnetic sensor and the magnet is varied in the first direction. That is, if the distance between the magnetic sensor and the magnet in the first direction is varied, a detection signal detected by the magnetic sensor in the second direction is not constant.